Earth phase

Earth phase
Partial Earth as seen from the Moon
Earthrise by Apollo 8 astronaut William Anders, December 1968. Earth at gibbous phase as seen from the Moon.

The Earth phase, Terra phase, terrestrial phase, or phase of Earth, is the shape of the directly sunlit portion of Earth as viewed from the Moon (or elsewhere extraterrestrially). From the Moon, the Earth phases gradually and cyclically change over the period of a synodic month (about 29.53 days), as the orbital positions of the Moon around Earth and of Earth around the Sun shift.[1][2][3][4][5][6]

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